It was designed by New South Wales Government Railways and opened in 1884, with William Robinson having built the original station buildings.

[3] Sydenham was built on a duplicated line from Illawarra Junction to Hurstville and opened as Marrickville on 15 October 1884.

The western platform contained a major 3rd class brick station building having a detached toilet block at each end separated by walled courtyards while the eastern platform contained a large 2nd class brick station building.

In 1907, the line from Edgeware Road to Sydenham was quadruplicated to serve the Belmore to Bankstown extension when it opened in 1909.

As the additional tracks were never utilised for the Eastern Suburbs Railway, they have been mainly used for the Bankstown line trains.

[3] It had been intended that the tracks on platforms 1 and 2 would extend along the alignment to Erskineville as an adjunct to the Eastern Suburbs railway.

Most East Hills trains now run via the Airport line, although some peak hour services continue to travel via Sydenham using these platforms.

[8] Immediately south of the station, the Metropolitan Goods Line to Port Botany crosses via a pratt truss bridge that opened in 1925, while beyond lies the XPT Service Centre.

[10] Metro services to Sydenham were originally planned to commence on 4 August 2024, [11][12] but was postponed due to failure to secure an approval from safety regulators.

This is connected to the main platform building via a recently roofed courtyard with painted brick walls both sides and a moulded stucco capping course and central curved section.

The platform building has timber framed double hung windows, some plain, some with single horizontal glazing bars to each sash.

The north awning has a timber tongue & grooved board ceiling and is clearly more recent, with modern steel posts and framing.

The current Station Master's office (which appears to have been a former waiting area) has a decorative pressed metal ceiling and cornices, a modern tiled floor, a notable marble mantelpiece to the chimney breast.

The building features timber framed double hung windows with moulded stucco heads and sills.

The surviving interior and exterior detailing of the 1884 platform buildings and awnings is considered rare on the Illawarra line, with other examples at St. Peters, Tempe and Rockdale.

[3] Sydenham railway station was listed on the New South Wales State Heritage Register on 2 April 1999 having satisfied the following criteria.

[3] The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales.

[3] The place possesses uncommon, rare or endangered aspects of the cultural or natural history of New South Wales.

[3] The place is important in demonstrating the principal characteristics of a class of cultural or natural places/environments in New South Wales.

The platform buildings, awnings, footbridge, stairs, and overbridge are representative of railway structure designs over time from 1884 to 1962.

[3] This Wikipedia article contains material from Sydenham Railway Station group, entry number 01254 in the New South Wales State Heritage Register published by the State of New South Wales (Department of Planning and Environment) 2018 under CC-BY 4.0 licence, accessed on 2 June 2018.